Plant Cell Reports最新文献

Waterlogging stands as a common environmental challenge, significantly affecting plant growth, yield, and, in severe cases, survival. In response to waterlogging stress, plants exhibit a series of intricate physiologic, metabolic, and morphologic adaptations. Notably, the gaseous phytohormone ethylene is rapidly accumulated in the plant submerged tissues, assuming an important regulatory factor in plant-waterlogging tolerance. In this review, we summarize recent advances in research on the mechanisms of ethylene in the regulation of plant responses to waterlogging stress. Recent advances found that both ethylene biosynthesis and signal transduction make indispensable contributions to modulating plant adaptation mechanisms to waterlogged condition. Ethylene was also discovered to play an important role in plant physiologic metabolic responses to waterlogging stress, including the energy mechanism, morphologic adaptation, ROS regulation and interactions with other phytohormones. The comprehensive exploration of ethylene and its associated genes provides valuable insights into the precise strategies to leverage ethylene metabolism for enhancing plant resistance to waterlogging stress.

Key message: The pathogenesis-related 1 gene of watermelon responds to the infection of ZYMV and contributes to the resistance of its host. Zucchini yellow mosaic virus (ZYMV; family Potyviridae) is a single-stranded positive-sense RNA virus that is a serious threat to cucurbits. Previously, we observed a hypersensitivity response (HR) in the systemic leaves of the 938-16-B watermelon line infected with ZYMV, distinct from the typical HR at infected sites. In this study, we confirmed that ZYMV accumulation in 938-16-B was significantly lower than in the susceptible line H1. Upon inoculation, the entry of ZYMV-eGFP into mesophyll cells is restricted into necrotic spots in leaves, indicating that resistance to ZYMV in 938-16-B is linked to the HR. Further, grafting experiments between 938-16-B and susceptible varieties were performed, and revealed an HR induction in susceptible varieties, suggesting the transfer of resistance signal(s) from 938-16-B to susceptible varieties. Through RNA-sequencing and proteomics analyses of the H1 scions on 938-16-B rootstock, a pathogenesis-related 1 (ClPR1) gene was identified. Specifically, ClPR1 expression is unique to ZYMV-infected 938-16-B. Repression of the expression of ClPR1 prevents an HR in 938-16-B. Conversely, overexpression of ClPR1 in susceptible varieties significantly reduces ZYMV accumulation, but an HR was not induced in susceptible line. Besides the virus, jasmonic acid (JA) can also trigger an HR in 938-16-B. Intriguingly, the expression of ClPR1 (Cla97C02G034020) is induced in both of 938-16-B and H1 by MeJA, rather than salicylic acid. These results suggest that HR is associated with the expression of ClPR1 and contributes to resistance to ZYMV in 938-16-B.

Key message: PlZAT10-PlCYP707A2 module promotes Paeonia lactiflora seeds germination. The herbaceous peony (Paeonia lactiflora) seeds exhibit double dormancy in the epicotyl and hypocotyl, which significantly inhibits the process of cultivation and breeding of new varieties. Nevertheless, the molecular mechanism underlying seed dormancy release in P. lactiflora remains to be fully identified. In this current study, we analyzed differentially expressed genes based on transcriptome data and selected the abscisic acid catabolic gene PlCYP707A2 for further investigation. The conserved domain of the protein indicated that PlCYP707A2 possessed a cytochrome P450 monooxygenase domain. Subcellular localization indicated that PlCYP707A2 was localized on the cytoplasm and cell membrane. Overexpression of PlCYP707A2 in P. lactiflora seeds decreased ABA contents and promoted seeds germination. The silencing of PlCYP707A2 resulted in seed dormancy and an alteration in the content of ABA. Moreover, yeast one-hybrid, electrophoretic mobility shift and dual-luciferase reporter assay revealed that PlZAT10 bound to the promoter of PlCYP707A2. In conclusion, the results demonstrated the mechanism of the PlZAT10-PlCYP707A2 module in regulating the dormancy release of P. lactiflora seeds, enriching relevant theories on seed dormancy and having significant implications for the herbaceous peony industry developing.

Key message: The SBP-box transcription factor PlSPL2 silencing in herbaceous peony enhanced stem strength by regulating xylem development, whereas its overexpression in tobacco resulted in weaker stem strength and undeveloped xylem. The strength of plant stems is a critical determinant of lodging resistance of plants, which significantly affects crop yield and cut-flower quality. Squamosa promoter binding (SBP) protein-like (SPL) transcription factors (TFs), participate in multiple regulatory processes, particularly in stem development. In this study, PlSPL2, an orthologous gene of Arabidopsis AtSPL2 in herbaceous peony, was isolated and found to contain a conserved SBP domain featuring two typical Zn-binding sites, as well as a nuclear localization sequence (NLS). Subsequently, transient infection of tobacco leaf epidermal cells using Agrobacterium confirmed the nuclear localization of PISPL2 protein. Additionally, gene expression analyses revealed that PlSPL2 was preferentially expressed in stems, and demonstrated a download trend in expression levels within vascular bundles during stem cell wall development. Furthermore, silencing of PlSPL2 in herbaceous peony enhanced stem strength. The silenced plants exhibited more developed xylems with wider radii and higher numbers of cell layers. Overexpression of PlSPL2 in tobacco, however, resulted in weaker stem strength, accompanied by a narrower radius of the xylem. These findings suggested that PlSPL2 was a negative regulator of herbaceous peony stem development, and its discovery and research could significantly contribute to a deeper understanding of stem growth and development mechanisms.

The ability to efficiently genetically modify plant species is crucial, driving the need for innovative technologies in plant biotechnology. Existing plant genetic transformation systems include Agrobacterium-mediated transformation, biolistics, protoplast-based methods, and nanoparticle techniques. Despite these diverse methods, many species exhibit resistance to transformation, limiting the applicability of most published methods to specific species or genotypes. Tissue culture remains a significant barrier for most species, although other barriers exist. These include the infection and regeneration stages in Agrobacterium, cell death and genomic instability in biolistics, the creation and regeneration of protoplasts for protoplast-based methods, and the difficulty of achieving stable transformation with nanoparticles. To develop species-independent transformation methods, it is essential to address these transformation bottlenecks. This review examines recent advancements in plant biotechnology, highlighting both new and existing techniques that have improved the success rates of plant transformations. Additionally, several newly emerged plant model systems that have benefited from these technological advancements are also discussed.

Key message: Based on transport inhibition and genome-wide analysis, 123 ABC transporters of Euphorbia lathyris were identified, and it was found that the PDR family members ElABCG39 mediated ingenol efflux. Identification of ingenol biosynthetic enzymes and transporters in plant is fundamental to realize its biosynthesis in chassis cells. At present, several key enzymes of the ingenol biosynthesis pathway have been identified, while the mechanisms governing the accumulation or transport of ingenol to distinct plant tissue compartments remain elusive. In this study, transport inhibition analyses were performed, along with genome-wide identification of 123 genes encoding ABC proteins in Euphorbia lathyris L., eventually discovering that a PDR transporter ElABCG39 mediates ingenol transmembrane transport and is localized on the plasma membrane. Expression of this protein in yeast AD1-8 promoted the transmembrane efflux of ingenol with strong substrate specificity. Furthermore, in ElABCG39 RNAi transgenic hairy roots, ingenol transmembrane efflux was significantly reduced and hairy root growth was inhibited. The discovery of the first Euphorbia macrocyclic diterpene transporter ElABCG39 has not only further improved the ingenane diterpenoid biosynthesis regulatory network, but also provided a new key element for ingenol production in chassis cells.

Key message: Melatonin and melatonin-mediated phytohormonal crosstalk play a multifaceted role in improving drought stress tolerance via molecular mechanisms and biochemical interactions in horticultural plants. The physical, physiological, biochemical, and molecular characteristics of plants are all affected by drought stress. Crop yield and quality eventually decline precipitously as a result. A phytohormone, melatonin, controls several plant functions during drought stress. However, the interactions between melatonin and other phytohormones, particularly how they control plant responses to drought stress, have not been clearly explored. This review explores the effects of melatonin and particular phytohormones on improving plant tolerance to drought stress. Specifically, the key melatonin roles in improved photosynthetic performance, better antioxidant activities, up-regulated gene expression, increased plant growth, and yield, etc., during drought stress have been elucidated in this review. Furthermore, this review explains how the intricate networks of melatonin-mediated crosstalk phytohormones, such as IAA, BR, ABA, GA, JA, CK, ET, SA, etc., enable horticultural plants to tolerate drought stress. Thus, this research provides a better understanding of the role of phytohormones, mainly melatonin, elucidates phytohormonal cross-talks in drought stress response, and future perspectives of phytohormonal contributions in plant improvements including engineering plants for better drought stress tolerance via targeting melatonin interactions.

Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (CRISPR/Cas9) genome-editing system has altered plant research by allowing for targeted genome alteration, and they are emerging as powerful tools for evaluating plant gene function and improving crop yield. Even though CRISPR/Cas9 cleavage and subsequent repair are effective ways to precisely replace genes and change base pairs in plants, the dominance of the non-homologous end-joining pathway (NHEJ) and homology-directed repair's (HDR) poor effectiveness in plant cells have restricted their use. Base editing is gaining popularity as a potential alternative to HDR or NHEJ-mediated replacement, allowing for precise changes in the plant genome via programmed conversion of a single base to another without the need for a donor repair template or double-stranded breaks. In this review, we primarily present the mechanisms of base-editing system, including their distinct types such as DNA base editors (cytidine base editor and adenine base editor) and RNA base editors discovered so far. Next, we outline the current potential applications of the base-editing system for crop improvements. Finally, we discuss the limitations and potential future directions of the base-editing system in terms of improving crop quality. We hope that this review will enable the researcher to gain knowledge about base-editing tools and their potential applications in crop improvement.

Key message: The proteomic analysis of PMeV-complex-infected C. papaya unveiled proteins undergoing modulation during the plant's development. The infection notably impacted processes related to photosynthesis and cell wall dynamics. The development of Papaya Sticky Disease (PSD), caused by the papaya meleira virus complex (PMeV-complex), occurs only after the juvenile/adult transition of Carica papaya plants, indicating the presence of tolerance mechanisms during the juvenile development phase. In this study, we quantified 1609 leaf proteins of C. papaya using a label-free strategy. A total of 345 differentially accumulated proteins were identified-38 at 3 months (juvenile), 130 at 4 months (juvenile/adult transition), 160 at 7 months (fruit development), and 17 at 9 months (fruit harvesting)-indicating modulation of biological processes at each developmental phase, primarily related to photosynthesis and cell wall remodeling. Infected 3- and 4-mpg C. papaya exhibited an accumulation of photosynthetic proteins, and chlorophyll fluorescence results suggested enhanced energy flux efficiency in photosystems II and I in these plants. Additionally, 3 and 4-mpg plants showed a reduction in cell wall-degrading enzymes, followed by an accumulation of proteins involved in the synthesis of wall precursors during the 7 and 9-mpg phases. These findings, along with ultrastructural data on laticifers, indicate that C. papaya struggles to maintain the integrity of laticifer walls, ultimately failing to do so after the 4-mpg phase, leading to latex exudation. This supports initiatives for the genetic improvement of C. papaya to enhance resistance against the PMeV-complex.

Key message: Transgenic Crambe abyssinica lines overexpressing γ-ECS significantly enhance tolerance to and accumulation of toxic metal(loid)s, improving phytoremediation potential and offering an effective solution for contaminated soil management. Phytoremediation is an attractive environmental-friendly technology to remove metal(loid)s from contaminated soils and water. However, tolerance to toxic metals in plants is a critical limiting factor. Transgenic Crambe abyssinica lines were developed that overexpress the bacterial γ-glutamylcysteine synthetase (γ-ECS) gene to increase the levels of non-protein thiol peptides such as γ-glutamylcysteine (γ-EC), glutathione (GSH), and phytochelatins (PCs) that mediate metal(loid)s detoxification. The present study investigated the effect of γ-ECS overexpression on the tolerance to and accumulation of toxic As, Cd, Pb, Hg, and Cr supplied individually or as a mixture of metals. Compared to wild-type plants, γ-ECS transgenics (γ-ECS1-8 and γ-ECS16-5) exhibited a significantly higher capacity to tolerate and accumulate these elements in aboveground tissues, i.e., 76-154% As, 200-254% Cd, 37-48% Hg, 26-69% Pb, and 39-46% Cr, when supplied individually. This is attributable to enhanced production of GSH (82-159% and 75-87%) and PC2 (27-33% and 37-65%) as compared to WT plants under AsV and Cd exposure, respectively. The levels of Cys and γ-EC were also increased by 56-67% and 450-794% in the overexpression lines compared to WT plants under non-stress conditions, respectively. This likely enhanced the metabolic pathway associated with GSH biosynthesis, leading to the ultimate synthesis of PCs, which detoxify toxic metal(loid)s through chelation. These findings demonstrate that γ-ECS overexpressing Crambe lines can be used for the enhanced phytoremediation of toxic metals and metalloids from contaminated soils.